Issue 34, 2017

Stabilization of ultra-small [Ag2]2+ and [Agm]n+ nano-clusters through negatively charged tetrahedrons in oxyfluoride glass networks: To largely enhance the luminescence quantum yields

Abstract

Herein, three different silver species were stably formed in SiO2–Al2O3–B2O3–Na2O–ZnF2–CaF2 glasses and were identified by their characteristic luminescence bands: violet blue luminescence (Ag+: 4d95s1 → 4d10), green white molecular fluorescence (molecule-like [Agm]n+, named ML-Ag) and orange molecular fluorescence ([Ag2]2+ pairs). Due to the relatively low aggregation degrees of [Agm]n+ and [Ag2]2+, non-radiative transitions were highly suppressed, and the PL quantum yields (QYs) of ML-Ag and [Ag2]2+ pairs reached 73.7% and 89.7%, respectively. The substitution of 0.5B2O3−0.5Na2O with SiO2 promoted the partial reduction of Ag+ to Ag0 and the subsequent aggregation of Ag+ and Ag0 to form [Agm]n+ (ML-Ag). The absence of Na2O also resulted in an increasing amount of Ag+–Ag+ pairs with closing interionic distance to form [Ag2]2+ in glass. According to the X-ray photoelectron spectra (XPS) and magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra, a solubility strategy and a charge compensation model were proposed to describe the transformations between different silver species. The formation of ML-Ag was further controlled via the solubility of Ag+ in glass, whereas [Ag2]2+ centers could be effectively produced by lowering the total amount of other competitive charge compensators, such as Na+, or by introducing negatively charged [BO4], [AlO4], and [ZnO4]2− tetrahedrons into the glass matrix.

Graphical abstract: Stabilization of ultra-small [Ag2]2+ and [Agm]n+ nano-clusters through negatively charged tetrahedrons in oxyfluoride glass networks: To largely enhance the luminescence quantum yields

Supplementary files

Article information

Article type
Paper
Submitted
18 Apr 2017
Accepted
30 May 2017
First published
30 May 2017

Phys. Chem. Chem. Phys., 2017,19, 22638-22645

Stabilization of ultra-small [Ag2]2+ and [Agm]n+ nano-clusters through negatively charged tetrahedrons in oxyfluoride glass networks: To largely enhance the luminescence quantum yields

R. Ma, J. Zhao, X. Chen, X. Qiao, X. Fan, J. Du and X. Zhang, Phys. Chem. Chem. Phys., 2017, 19, 22638 DOI: 10.1039/C7CP02531A

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